Hello @damon-stadiumgat,
Welcome to the Community. I can help you import bank transactions using CSV in QuickBooks Online.
You usually get an error when uploading data when there's an issue with the mapping and formatting. I recommend reviewing the file to ensure the details are correct.
Please note there are required columns by QuickBooks. These are the Date, Description, and Amount (or Credit and Debit).
Also, not all banks create their CSV files the same way, so you may need to make some changes to get your transactions in. Check out this link to learn more about how to correct your data before uploading to QuickBooks: Common errors for importing bank transactions using CSV.
Once reviewed, upload your file again. You should be able to bring over banking data successfully.
Keep in mind there's a file limit for the upload. For more information about decreasing the file size, visit this article: Manually upload transactions into QuickBooks Online.
Feel free to hit that Reply button if you need further assistance fixing the import error. I'll be happy to help you some more. Have a great day ahead.
